Flame retardant, high precision resin mechanical part for use in an office automation machine

ABSTRACT

Disclosed is a flame retardant, high precision resin mechanical part for use in office automation machines required to function with high accuracy and high precision, which is made by injection molding a thermoplastic resin composition comprising: (A) an amorphous thermoplastic resin; (B) an inorganic filler in a scale form; and (C) a specific phosphoric acid ester in which phosphoric acid ester groups are bonded through a bisphenol.

BACKGROUND OF THE INVENTION

1. Technical Fields

The present invention relates to a flame retardant, high precision resinmechanical part for use in an office automation machine, which is madeby injection molding a thermoplastic resin composition. Moreparticularly, the present invention is concerned with a flame retardant,high precision resin mechanical part for use in office automationmachines required to function with high accuracy and high precision,which part is made by injection molding a thermoplastic resincomposition comprising: (A) an amorphous thermoplastic resin; (B) aninorganic filler in a scale form; and (C) a specific phosphoric acidester. The high precision resin mechanical part of the present inventionis free from conventionally experienced disadvantages, such asvolatilization of a flame retardant contained in the resin, smokingcaused by the volatilization of the flame retardant and occurrence of MD(mold deposit) during the production thereof by molding, and bleeding ofthe flame retardant during the use thereof. Further, the mechanical partof the present invention is unlikely to suffer from warpage, and has anadvantageously small shrinkage ratio during the production thereof bymolding. Therefore, the mechanical part of the present invention has notonly high precision but also various excellent mechanical properties,such as extremely low anisotropy in linear expansion coefficient, andexcellent vibration characteristics. The high precision resin mechanicalpart of the present invention can be advantageously used as a mechanicalpart for high precision machines which are required to function withhigh accuracy and high precision even under various stringentconditions. Examples of such high precision machines include computers,game machines, sound-reproducing systems, audio-visual machines,copiers, printers, facsimile machines, personal computers, wordprocessors, portable communication apparatus and composite machinescomposed thereof.

2. Technical Background

Recently, in various fields, such as automobiles, office machines,computers and household electric appliances, it has been attempted tosubstitute a resin part for parts which have conventionally been madefrom a metallic material, such as sheet metals and die-casted aluminum.Such an attempt has been made because a part made from a resin isadvantageous in that such a resin part has not only light weight, butalso can be produced with high productivity at low cost. Therefore,there is an increasing demand for reinforced resins which can besubstituted for metallic materials in producing a mechanical part.Particularly, there is a strong demand for reinforced resins which canbe used for producing mechanical parts for OA (office automation)machines, such as copiers, printers, facsimile machines, CD-ROMs,personal computers, word processors and communication apparatuses. Thecopiers, printers and facsimile machines are OA machines which areequipped with a printing mechanism, such as a dry-type, diazo-type, LB(laser beam)-type, BJ (bubble jet)-type, dot-type or heat sensitive-typeprinting mechanism.! In accordance with such a strong demand forreinforced resins, it has been intensively studied to develop amorphousthermoplastic resins (e.g., a reinforced, flame retardant polyphenyleneether resin and a reinforced, flame retardant polycarbonate resin) whichhave excellent mechanical properties and excellent molded formcharacteristics, so as to produce from such resins mechanical partswhich have conventionally been produced from metallic materials, such assheet metals and die-casted aluminum.

It is a requisite that a resin mechanical part of an OA machine haveexcellent molded form characteristics, mechanical properties (e.g.,rigidity and strength), heat resistance, flame retardancy, dimensionalprecision and dimensional stability.

Among these properties, the requirements for dimensional precision anddimensional stability are most strict. For example, with respect to themechanical part of a CD-ROM, when a traverse base, which guides andholds an optical lens unit, has a dimensional strain, the misreading ofdata from the CD occurs. With respect to the internal mechanical partsof OA machines having a laser beam-type printing mechanism, such as acopier, a printer and a facsimile machine, when such mechanical partshave a dimensional strain, the misreading of data is caused, therebyleading to disadvantages, such as blurring of the printed image.Further, with respect to the internal mechanical parts of OA machineshaving a diazo-type, bubble jet-type or heat sensitive-type printingmechanism, when such mechanical parts have a dimensional strain, theprinted letter becomes blurred.

With respect to such mechanical parts as mentioned above, it is requiredthat the dimensional precision thereof be such that any errors ordeviations must be only on the order of several tens of μm.

When it is attempted to produce a mechanical part of an OA machine froman amorphous thermoplastic resin in accordance with a conventionalmethod, the following problems are encountered.

As a conventional technique for imparting a resin with high rigidity andstrength, there has been known a method in which a fibrous inorganicfiller, such as a glass fiber, is blended with a resin. This techniquehas disadvantages as follows. That is, when a fibrous inorganic fillerhaving a large aspect ratio (length/thickness), such as an inorganicfiber or a whisker, is added to the resin, and the resultant resincomposition containing such a fibrous inorganic filler is subjected toinjection molding, the fibrous inorganic filler is oriented along thedirection of flow of the resin. Accordingly, an obtained molded articleinevitably becomes anisotropic with respect to the rigidity, strength,shrinkage ratio (occurring during molding thereof) and linear expansioncoefficient. Therefore, it is likely that the rigidity and strength ofthe molded article become poor and that the shaped article sufferswarpage which leads to a dimensional deformation or dimensional strainof the molded article. Further, this technique is also disadvantageousin that the anisotropy of linear expansion coefficient causes the moldedarticle to be susceptible to a change in temperature. Specifically, themolded article, which is anisotropic in linear expansion coefficient,easily suffers dimensional deformation when the temperature changes, sothat it is poor in dimensional stability.

On the other hand, when a conventional inorganic filler having a smallaspect ratio, such as glass beads and calcium carbonate, is used, theobtained molded article is improved with respect to dimensionalprecision and dimensional stability. However, this molded article alsois disadvantageous in that it has poor rigidity and strength.

For the purpose of improving the flame retardancy of an amorphousthermoplastic resin, a flame retardant is generally used. For example, aconventional halogenated aromatic compound, such as tetrabromobisphenolA (TBA) and polybromobiphenyl oxide (PBBO), has been widely used toimprove the flame retardancy of an amorphous thermoplastic resin withthe exception of polyphenylene ether resin. However, with respect to notonly the halogen type flame retardant, but also antimony trioxide (Sb₂O₃), which is generally used as an auxiliary flame retardant for thehalogen type flame retardant, is undesirable in view of the adverseinfluence on the environment and the safety to human body. Therefore, inthe market, there is an increasing tendency to refrain the use of theabove-mentioned halogen type flame retardant and antimony trioxide.Meanwhile, there is known a polyphenylene ether resin composition or apolycarbonate resin composition, in which, as a non-halogen type flameretardant, a phosphorus compound is employed (see, for example, G.B.Patent Application Publication No. 2043083 and U.S. Pat. No. 5,204,394).Specifically, an organic phosphoric acid ester compound, such astriphenyl phosphate, cresyl diphenyl phosphate and tricresyl diphenylphosphate, has been widely used as the flame retardant. However, theresin composition containing the organic phosphoric acid ester compoundis disadvantageous in that the phosphoric acid ester compound is likelyto be volatilized or generate smoke during molding of the resincomposition containing the same and that MD (mold deposit) is likely tooccur on the inner surface of a mold cavity. Further, a molded articleproduced from the resin composition containing such a phosphoric acidester compound has a defect in that the phosphoric acid ester compoundbleeds out on the surface of the molded article (bleeding), therebycausing the molded article to suffer discoloration, blistering, crackingand the like.

As a method for solving the above-mentioned problems, it has beenproposed to employ, as a flame retardant, an organic phosphorus compoundhaving a high molecular weight. Specifically, it has been attempted toemploy, as a flame retardant, a phosphorus compound having a highmolecular weight, such as tri(2,6-dimethylphenyl)phosphate,resorcinol-bisdiphenyl phosphate and tribiphenyl phosphate (see, forexample, International Patent Application Publication No. 94/03535corresponding to European Patent Application Publication No. 0 611 798).However, these organic phosphorus compounds are disadvantageous in thatsuch a compound must be used in a large amount in order to render flameretardant the resin, and that when the resin composition, which isrendered flame retardant with a phosphoric acid ester compound, issubjected to molding, corrosion of a metallic mold is caused during themolding thereof. Further, a mechanical part produced from such a resincomposition has poor resistance to moisture and heat. Specifically, whenthe above-mentioned mechanical part is placed under high temperature andhigh humidity conditions, the resin of the mechanical part absorbs waterand/or the flame retardant contained in the resin undergoesdenaturation, thereby deteriorating various properties of the resin,such as electrical characteristics, flame retardancy and dimensionalstability. As is understood from the above, the conventional techniqueshave various problems and it has been impossible to substitute a resinpart containing a non-halogen type retardant for a metallic mechanicalpart for an OA machine. That is, it has been extremely difficult toproduce a mechanical part, from a resin composition containing anon-halogen type flame retardant, which part has excellent mechanicalproperties, dimensional precision, molded form characteristics and flameretardancy.

SUMMARY OF THE INVENTION

In these situations, the present inventors have made extensive andintensive studies with a view toward developing a flame retardant, highprecision resin mechanical part which is free from the above-mentionedproblems accompanying the conventional resin mechanical parts. As aresult, it has unexpectedly been found that a mechanical part, which isproduced by injection molding a thermoplastic resin compositioncomprising an amorphous thermoplastic resin, an inorganic filler (e.g.,glass flakes) in a scale form, and a specific phosphoric acid ester as aflame retardant in which phosphoric acid ester groups are linked througha bisphenol, is advantageous in that such a resin mechanical part isfree from conventionally experienced disadvantages, such asvolatilization of a flame retardant contained in the resin, smokingcaused by the volatilization of the flame retardant and occurrence of MD(mold deposit) during the molding thereof, and bleeding of the flameretardant during the use thereof; that such a mechanical part isunlikely to suffer from warpage, and has an advantageously smallshrinkage ratio during the production thereof by molding; and that,therefore, such a mechanical part has not only high precision but alsovarious excellent mechanical properties, such as extremely lowanisotropy in linear expansion coefficient, and excellent vibrationcharacteristics, so that the resin mechanical part can be advantageouslyused as a mechanical part for high precision machines which are requiredto function with high accuracy and high precision even under variousstringent conditions. The present invention has been completed, based onthis novel finding.

Accordingly, it is a primary object of the present invention to providea flame retardant, high precision resin mechanical part for use in OAmachines, which has not only excellent mechanical properties but alsohigh dimensional precision, as required for a mechanical part of an OAmachine, and which, therefore, can be substituted for a conventionalmechanical part which is made from metallic materials (such as sheetmetals and die-casted aluminum).

The foregoing and other objects, features and advantages of the presentinvention will be apparent to those skilled in the art from thefollowing detailed description and appended claims taken in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1(a) is a diagrammatic perspective view of a tray-shaped mechanicalpart produced in Examples 1 through 30;

FIG. 1(b) is a diagrammatic cross-sectional view of the tray-shapedmechanical part of FIG. 1(a), taken along line IB--IB; and

FIG. 2 is a diagrammatic perspective view of a mechanical part, i.e., achassis for holding an optical element, produced in Examples 31 to 36.

In FIG. 1 (a) and l(b), the characters designate the following parts andportions.

A through F: Measurement sites at which the dimensional precision ismeasured At each of A through D, the dimensional precision is measuredin terms of a gap between a molded article and a mold platen; and ateach of E and F, the dimensional precision is measured in terms of adifference between the actual dimension of a molded article and thepredetermined (designed) dimensional value (4.1 mm and 6.1 mm,respectively) shown in FIG. 1(b).!

G: Site of the molded article corresponding to the pin gate of a mold

In FIG. 2, the hatched portion indicates a section at which measurementof flatness is done.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, there is provided a flameretardant, high precision resin mechanical part for use in officeautomation machines required to function with high accuracy and highprecision, which is made by injection molding a thermoplastic resincomposition comprising:

(A) 100 parts by weight of an amorphous thermoplastic resin;

(B) 5 to 150 parts by weight of an inorganic filler in a scale form; and

(C) 3 to 50 parts by weight of a phosphoric acid ester represented bythe following formula (I): ##STR1## wherein each of Q¹, Q², Q³ and Q⁴independently represents a hydrogen atom or an alkyl group having 1 to 6carbon atoms; each of R¹, R², R³ and R⁴ independently represents amethyl group or a hydrogen atom; n represents an integer of 1 or more;each of n1 and n2 independently represents an integer of from 0 to 2;and each of m1, m2, m3 and m4 independently represents an integer offrom 1 to 3.

For ease in understanding of the present invention, the essentialconstruction and various preferred embodiments of the present inventionare enumerated below.

1. A flame retardant, high precision resin mechanical part for use inoffice automation machines required to function with high accuracy andhigh precision, which is made by injection molding a thermoplastic resincomposition comprising:

(A) 100 parts by weight of an amorphous thermoplastic resin;

(B) 5 to 150 parts by weight of an inorganic filler in a scale form; and

(C) 3 to 50 parts by weight of a phosphoric acid ester represented bythe following formula (I): ##STR2## wherein each of Q¹, Q², Q³ and Q⁴independently represents a hydrogen atom or an alkyl group having 1 to 6carbon atoms; each of R¹, R², R³ and R⁴ independently represents amethyl group or a hydrogen atom; n represents an integer of 1 or more;each of n1 and n2 independently represents an integer of from 0 to 2;and each of m1, m2, m3 and m4 independently represents an integer offrom 1 to 3.

2. The flame retardant, high precision resin mechanical part accordingto item 1 above, wherein the injection molding is gas-assisted injectionmolding.

3. The flame retardant, high precision resin mechanical part accordingto item 1 above, wherein the inorganic filler in a scale form iscomprised of glass flakes.

4. The flame retardant, high precision resin mechanical part accordingto item 1 above, wherein the inorganic filler in a scale form iscomprised of mica flakes.

5. The flame retardant, high precision resin mechanical part accordingto item 1 above, wherein the inorganic filler in a scale form iscomprised of glass flakes and mica flakes.

6. The flame retardant, high precision resin mechanical part accordingto any one of items 1 to 5 above, wherein the thermoplastic resincomposition further comprises a fibrous reinforcing filler, and whereinthe total weight of the inorganic filler in a scale form and the fibrousreinforcing filler is 150 parts by weight or less.

7. The flame retardant, high precision resin mechanical part accordingto item 6 above, wherein the fibrous reinforcing filler is present in anamount of from 25 to 75% by weight, based on the total weight of theinorganic filler in a scale form and the fibrous reinforcing filler.

It is a requisite that the amorphous thermoplastic resin compositionconstituting the high precision mechanical part of the present inventionfor use in an office automation machine contain an inorganic filler in ascale form. Examples of inorganic fillers in a scale form include glassflakes and mica flakes.

With respect to glass flakes for use as the inorganic filler in a scaleform, it is desired that the glass flakes incorporated in the resincomposition have a major diameter of 1000 μm or less, preferably 1 to500 μm, and have a weight average aspect ratio (ratio of a weightaverage major diameter to a weight average thickness) of 5 or more,preferably 10 or more, more preferably 30 or more. When glass flakes aremixed with other components to produce the resin composition, glassflakes undergo breakage, so that the size of the glass flakes isdecreased. Measurement of the major diameter and thickness of glassflakes incorporated in a resin composition can be done by a method inwhich the resin composition is dissolved and subjected to filtration tothereby collect the glass flakes, and the dimensional characteristics ofglass flakes are examined, using an optical microscope.

Examples of commercially available glass flakes which can be suitablyemployed in the present invention include Micro Glass Fleka (tradenameof glass flakes sold by Nippon Sheet Glass Co., Ltd., Japan). In thepresent invention, commercially available glass flakes can be used assuch, but commercially available glass flakes may be appropriatelypulverized before incorporation into a resin composition. When glassflakes have a major diameter of more than 1000 μm, it becomes difficultto uniformly mix the glass flakes with a resin, so that it is possiblethat the mechanical properties of a molded resin article becomenon-uniform. When glass flakes have an aspect ratio of less than 5, theheat distortion temperature of the molded resin article is notsatisfactorily increased, and the Izod impact strength and rigidity tendto be low. For improving the compatibility of glass flakes with a resin,glass flakes which have been surface-treated with a suitable couplingagent may be used. Examples of coupling agents include a silane typecoupling agent (e.g., an aminosilane type coupling agent) and a titanatetype coupling agent.

Mica employable in the present invention is in a scale form. Forexample, Suzorite Mica (manufactured and sold by SUZORITE MICA PRODUCTS,INC., Canada) can be suitably employed as mica flakes. It is preferredthat mica flakes have a weight average diameter of 1000 μm or less,preferably 500 μm or less, more preferably 200 μm or less. From theviewpoint of improving rigidity, it is preferred that mica flakes have aweight average aspect ratio (weight average diameter of flakes/weightaverage thickness of flakes) of 10 or more, preferably 30 or more, morepreferably 100 or more. The lower limit of the weight average diameterof commercially available mica flakes is about 20 μm. As in the case ofglass flakes, when mica flakes are mixed with other components toproduce the resin composition, mica flakes undergo breakage, so that thesize of the mica flakes is decreased. Measurement of the size of micaflakes incorporated in a resin composition can be done by the samemethod as in the case of glass flakes. For improving the compatibilityof mica flakes are mixed with a resin, mica flakes which have beensurface-treated with coupling agents, such as those as mentioned above,can be suitably employed.

The resin composition constituting the mechanical part of the presentinvention for use in an office automation machine contains an inorganicfiller in a scale form in an amount of 5 to 150 parts by weight,preferably 10 to 100 parts by weight, more preferably 20 to 70 parts byweight, per 100 parts by weight of the amorphous thermoplastic resin.When the amount of the inorganic filler is less than 5 parts by weight,the rigidity is unsatisfactory and the linear expansion coefficient isnot satisfactorily improved. On the other hand, when the amount of theinorganic filler is more than 150 parts by weight, a uniform dispersionof the inorganic filler is difficult, so that the molding properties ofthe resin composition and the appearance of the shaped article becomepoor. When the amount of the inorganic filler is from 20 to 70 parts byweight, the most preferred balance of the molded form characteristics,thermal characteristics, mechanical properties and dimensional precisioncan be obtained.

In the present invention, for improving the strength of the mechanicalpart, the thermoplastic resin composition may further contain a fibrousreinforcing filler and, in this case, the total weight of the inorganicfiller in a scale form and the fibrous reinforcing filler is 150 partsby weight or less.

In the present invention, the inorganic filler and fibrous reinforcingfiller can be used in various manners. For example, glass flakes can beused alone; a combination of glass flakes and a fibrous reinforcingfiller can be used; a combination of glass flakes and mica flakes can beused; mica flakes can be used alone; a combination of mica flakes and afibrous reinforcing filler can be used; and a combination of glassflakes and mica flakes and a fibrous reinforcing filler can be used.When mica flakes are used alone, the mechanical part obtained has a highdimensional precision, but the mechanical properties, especially Izodimpact strength, of the mechanical part tend to be low. Therefore, whenmica flakes are used as an inorganic filler in a scale form, it ispreferred that at least one member selected from the group consisting ofglass flakes and a fibrous reinforcing filler be also employed.

Examples of fibrous reinforcing fillers which are employable incombination with an inorganic filler in a scale form include fibrousreinforcing agents, such as glass fibers, carbon fibers, ceramic fibersand metallic fibers. From the viewpoint of economy, improvement inmolding properties and a good balance of mechanical properties of theresin composition, glass fibers are most preferred as a fibrousreinforcing filler. With respect to the diameter and average length ofglass fibers, there is no particular limitation. However, from theviewpoint of improving the dimensional precision of the mechanical part,it is preferred that glass fibers have a relatively short length.Specifically, the average length of glass fibers incorporated in a resincomposition is preferably 0.1 to 1 mm, more preferably 0.15 to 0.7 mm.When a fibrous reinforcing filler is employed, it is preferred that thefibrous reinforcing filler be present in an amount of from 25 to 75% byweight, preferably 25 to 50% by weight, based on the total weight of theinorganic filler in a scale form and the fibrous reinforcing filler.When the amount of the fibrous reinforcing filler is more than 75% byweight, based on the total weight of the inorganic filler in a scaleform and the fibrous reinforcing filler, the dimensional precision(shrinking ratio in molding, and anisotropy of the linear expansioncoefficient) cannot be satisfactorily improved.

The phosphoric acid ester to be used in the present invention isrepresented by formula (I) above.

In formula (I), it is preferred that each of Q¹, Q², Q³ and Q⁴ be amethyl group.

In formula (I), n represents an integer of 1 or more. The heatresistance and processability of the resin composition produced vary,depending on the n value. Illustratively stated, when the n valuebecomes large, the heat resistance of the resin composition becomeshigh, while the processability becomes low. On the other hand, when then value becomes small, the above tendencies are reversed. A preferredrange of n is 1 to 5. A mixture of the phosphoric acid esters havingdifferent n values can also be used.

In the present invention, the phosphoric acid esters represented byformula (I) may be used individually or in combination.

The phosphoric acid ester to be used in the present invention has astructure in which phosphoric acid ester groups are bonded with eachother through a bisphenol, and has a monofunctional phenol at terminalsthereof.

Examples of bisphenols include 2,2-bis(4-hydroxyphenyl)propane(so-called bisphenol A), 2,2-bis(4-hydroxy-3-methylphenyl)propane,bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3,5-dimethylphenyl)methaneand 1,1-bis(4-hydroxyphenyl)ethane. Of these, bisphenol A is especiallypreferred.

Examples of monofunctional phenols include phenol, a monoalkylphenol, adialkylphenol and a trialkylphenol. The monofunctional phenols can beused individually or in combination. Especially, phenol, cresol,dimethylphenol (mixed xylenol), 2,6-dimethylphenol and trimethylphenolare preferred.

As mentioned above, the phosphoric acid ester to be used in the presentinvention has a structure in which phosphoric acid ester groups arebonded to each other through a bisphenol. Due to this structure, thevolatilization of the phosphoric acid ester is largely suppressed.Further, the phosphoric acid ester exhibits high performances which havenot been achieved by conventional polyphosphates having a structurewherein phosphoric acid ester groups are bonded to each other throughresorcinol or hydroquinone. Specifically, the mechanical part of thepresent invention, which is produced by molding the resin compositioncontaining the specific phosphoric acid ester, is prevented fromdeterioration of appearance (e.g., discoloration and blistering), suchas has been experienced in the case of a resin composition containingthe conventional polyphosphate when allowed to stand under hightemperature and high humidity conditions.

Further, in the present invention, when a molded article is producedfrom a resin composition containing a phosphoric acid ester comprising,as a monofunctional phenol, a monoalkylphenol, dialkylphenol or atrialkylphenol, the obtained molded article is further improved withrespect to thermal stability and resistance to hydrolysis as compared tothe molded article produced from a resin composition comprising aphosphoric acid ester compound having an unsubstituted monofunctionalphenol at terminals thereof.

In the present invention, when the phosphoric acid ester havingphosphoric acid groups bonded through a bisphenol and having analkyl-substituted monofunctional phenol at terminals thereof, theobtained molded article exhibits excellent characteristics such that themolded article is prevented from deterioration of properties, such aselectrical characteristics, flame retardancy and appearance, even whenthe molded article is contacted with moisture under heated conditions.

With respect to the molded articles produced from a resin compositionwhich contains a conventional organic phosphoric acid ester compoundhaving only a feature of high molecular weight, such asresorcinol-polyphosphate and hydroquinone-polyphosphate, the followingproblems are encountered. That is, such a resin composition has poorthermal stability, thereby causing a reaction between the phosphoricacid ester compound and the resin during the molding thereof. As aresult, the gelation with respect to the resin is caused, so that itbecomes impossible to produce a molded article from the resinefficiently under high temperature conditions. Further, the phosphoricacid ester compound is likely to be decomposed during the molding of theresin, thereby forming an acidic components, e.g., a phosphoric acid,which causes decomposition of the resin. Accordingly, the molecularweight and various properties of the resin are lowered, so that theresultant molded article has not only low practicability but also poorlong-term stability. In addition, such a resin composition isdisadvantageous in that the acidic compound formed by the decompositionof the phosphoric acid ester causes corrosion of various parts andportions of a molding machine, which are contacted with the resincomposition, such as metallic parts thereof (e.g., a barrel and a screw)and an inner wall surface of the mold cavity, and that when a moldedarticle produced from such a resin composition is contacted with ametallic part of other articles during the use of the molded article,corrosion of the metallic part is likely to occur.

On the other hand, the high precision resin mechanical part of thepresent invention does not suffer hydrolysis during the productionthereof by molding under high temperature and high humidity conditions,and has excellent thermal stability during the production thereof bymolding, so that the mechanical part is free from conventionallyexperienced disadvantages, such as volatilization of the flame retardantcontained in the resin, smoking caused by the volatilization of theflame retardant and occurrence of MD (mold deposit) during theproduction thereof by molding. Further, the mechanical part of thepresent invention is unlikely to suffer from the lowering of properties,such as electrical characteristics, flame retardancy and appearance ofthe shaped article, which is generally caused when the resin absorbswater under the high temperature and high humidity conditions, asmentioned above. In the present invention, the decomposition of theresin composition is markedly suppressed. Accordingly, the mechanicalpart of the present invention is unlikely to cause corrosion of themetallic parts or portions of the molding machine and corrosion of themetallic portion of other products which is contacted with the moldedarticle.

In the present invention, the phosphoric acid ester represented byformula (I) can be obtained by reacting a bisphenol and a monofunctionalphenol with phosphorus oxychloride. With respect to the method forproducing a phosphoric acid ester represented by formula (I), referencecan be made to , for example, U.S. Pat. No. 3,492,373.

In the amorphous thermoplastic resin composition which constitutes thehigh precision resin mechanical part (for use in OA machines) of thepresent invention, the phosphoric acid ester is used in an amount offrom 3 to 50 parts by weight, preferably from 5 to 20 parts by weightper 100 parts by weight of the amorphous thermoplastic resin. When thephosphoric acid ester is used in an amount which is smaller than theabove range, the obtained mechanical part becomes unsatisfactory withrespect to the flame retardancy. Meanwhile, when the phosphoric acidester is used in an amount which exceeds the above range, the obtainedmechanical part becomes disadvantageously low with respect to theresistance to heat.

In the present invention, a phosphoric acid ester other than representedby formula (I) can be used as long as the effects of the presentinvention are not impaired. The total weight of the phosphoric acidester represented by formula (I) and the other phosphoric acid ester isfrom 3 to 50 parts by weight, per 100 parts by weight of component (A).A phosphoric acid ester other than represented by formula (I) cangenerally be used in an amount of 50% by weight or less, preferably 30%by weight or less, based on the total weight of the phosphoric acidester represented by formula (I) and the other phosphoric acid ester.Examples of phosphoric acid esters other than represented by formula (I)include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate,cresyldiphenyl phosphate, dicresylphenyl phosphate,hydroxyphenyldiphenyl phosphate and compounds obtained by a modificationthereof with a substituent, and condensation-type phosphoric acidesters.

With respect to the amorphous thermoplastic resin to be used in thepresent invention, there is no particular limitation as long as themoldability of the resin composition and the characteristics of the highprecision resin mechanical part produced therefrom are satisfactory.However, from the viewpoint of the high compatibility of the resin withthe phosphoric acid ester represented by formula (I), (a) apolyphenylene ether resin, (b) a polycarbonate resin or (c) a styreneresin, is preferably used.

(a) Polyphenylene ether resin (hereinafter referred to simply as "PPEresin") means a PPE resin or a resin composition comprised mainly of aPPE resin and a polystyrene resin (hereinafter referred to simply as "PSresin"). If desired, the resin composition may contain a small amount ofpolyethylene or the like.

As the PPE resin, a phenylene ether homopolymer or copolymer comprisinga recurring unit represented by formula (II-1) and/or (II-2) can beused: ##STR3## wherein each of R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ independentlyrepresents an alkyl group having 1 to 4 carbon atoms, an aryl grouphaving 6 to 8 carbon atoms, a halogen atom or a hydrogen atom, providedthat R⁹ and R¹⁰ do not simultaneously represent a hydrogen atom.

Representative Examples of PPE resins include homopolymers, such aspoly(2,6-dimethyl-1,4-phenylene)ether,poly(2-methyl-6-ethyl-1,4-phenylene)ether,poly(2-ethyl-6-n-propyl-1,4-phenylene)ether,poly(2,6-di-n-propyl-1,4-phenylene)ether,poly(2-methyl-6-n-butyl-1,4-phenylene)ether,poly(2-ethyl-6-isopropyl-1,4-phenylene)ether andpoly(2-methyl-6-hydroxyethyl-1,4-phenylene)ether. Of these,poly(2,6-dimethyl-1,4-phenylene)ether is especially preferred.

Further, a polyphenylene ether copolymer comprised mainly of apolyphenylene structure which is obtained by copolymerizing analkyl-substituted phenol (e.g., 2,3,6-trimethylphenol) represented byformula (II-3) with, for example, o-cresol: ##STR4## wherein each ofR¹¹, R¹², R¹³ and R¹⁴ independently represents an alkyl group having 1to 4 carbon atoms, a halogen atom or a hydrogen atom, provided that R¹¹,R¹², R¹³ and R¹⁴ do not simultaneously represent a hydrogen atom.

With respect to PPE resins, reference can be made to, for example, U.S.Pat. No. 4,788,277.

The above-mentioned PPE resin can be used in the form of a graftcopolymer. For example, a graft copolymer in which a styrene compound isgrafted onto the PPE resin, or a graft copolymer in which a copolymer ofa styrene compound and a compound copolymerizable therewith (e.g.,maleic anhydride) is grafted onto the PPE resin. With respect to thegrafting method, reference can be made to, for example, U.S. Pat. No.4,097,556.

(b) The polycarbonate resin (hereinafter referred to simply as "PCresin") is a polymer comprising a recurring unit represented by formula(III-1): ##STR5## wherein Z represents a bond, or an alkylene having 1to 8 carbon atoms, an alkylidene having 2 to 8 carbon atoms, acycloalkylene having 5 to 15 carbon atoms, SO₂, SO, O, CO or a grouprepresented by formula (III-2); each X independently represents ahydrogen atom or an alkyl group having 1 to 8 carbon atoms; and each ofa and b independently represents an integer of from 0 to 4. ##STR6##

The PC resin can be produced, for example, by the reaction of abifunctional phenol with a carbonate precursor (e.g., phosgene) or bythe ester exchange reaction of a bifunctional phenol with anothercarbonate precursor (e.g., diphenyl carbonate) in a solvent, such asmethylene chloride, in the presence of a conventional acid acceptor andmolecular weight modifier.

Examples of bifunctional phenols include 2,2-bis(4-hydroxyphenyl)propane(so-called bisphenol A), hydroquinone, 4,4'-dihydroxydiphenyl,bis(4-hydroxyphenyl)alkane, bis(4-hydroxyphenyl)cycloalkane,bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone,bis(4-hydroxyphenyl)sulfoxide and bis(4-hydroxyphenyl)ether. Of these,bisphenol A and a mixture of bisphenol A with a bifunctional phenolother than bisphenol A are preferred. In addition, a homopolymer of thebifunctional phenol, a copolymer of two or more bifunctional phenols, ora mixture of the homopolymer and the copolymer may be used. Further, thePC resin to be used in the present invention may include a thermoplasticrandom branched polycarbonate obtained by reacting a multifunctionalaromatic compound with a carbonate precursor, or with a carbonateprecursor and a bifunctional phenol. With respect to the bifunctionalphenol, reference can be made to, for example, Unexamined JapanesePatent Application Laid-Open specification Nos. 2-115262 and 63-289056.

In the present invention, the above-mentioned PC resin can be mixed witha styrene resin (such as a PS resin, a HIPS resin, an AS resin, an ABSresin and/or the like), a PPE resin, a polyolefin resin, a polyamideresin, a thermoplastic elastomer, polyethylene telephthalate,polybutylene telephthalate, an acrylic resin, a phenolic resin, phenolicnovolak and/or the like. However, the resins which can be mixed with thePC resin are not limited to those mentioned above. Of the above resins,an ABS resin, an HIPS resin and an AS resin are especially preferred formixing with the PC resin.

(c) As a styrene resin to be used in the present invention, a vinylaromatic polymer or a rubber modified vinyl aromatic polymer is used.

Examples of vinyl aromatic polymers include polystyrene, a polymer ofstyrene substituted with an alkyl at a nucleus thereof (such aso-methylstyrene, p-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene,ethylstyrene or p-tert-butylstyrene), and a polymer of anα-alkyl-substituted styrene (such as α-methylstyrene orα-methyl-p-methylstyrene); and a copolymer of at least one of theabove-mentioned substituted styrenes and at least one of vinyl compoundsother than the vinyl aromatic polymers. Examples of such vinyl compoundscopolymerizable with the vinyl aromatic polymer include a methacrylicacid ester (such as methyl methacrylate or ethyl methacrylate), anunsaturated nitrile compound (such as acrylonitrile andmethacrylonitrile), and an acid anhydride (such as maleic anhydride). Ofthese, polystyrene, and a styrene-acrylonitrile copolymer (AS resin) arepreferred.

Examples of rubber modified vinyl aromatic polymers includepolybutadiene, a styrene-butadiene copolymer, a rubber-modifiedstyrene-acrylonitrile copolymer (ABS resin), polyisoprene, abutadiene-isoprene copolymer, natural rubber, and an ethylene-propylenecopolymer. Of these, polybutadiene, a styrene-butadiene copolymer and arubber-modified styrene-acrylonitrile copolymer (ABS resin) arepreferred. Particularly, a rubber-modified polystyrene containingpolybutadiene in which not less than 10% of the double bonds ishydrogenated (that is, a HIPS resin), is especially preferred because ofexcellent thermal stability thereof. With respect to the method forproducing an HIPS resin, reference can be made to, for example, U.S.Pat. Nos. 4,185,049, 3,346,520, 2,862,906, 3,243,481 and 3,903,202.

With respect to the method for preparing a thermoplastic resincomposition by combining the components defined above, i.e., anamorphous thermoplastic resin, a phosphoric acid ester represented byformula (I) and an inorganic filler in a scale form, and optionally afibrous reinforcing filler, there is no specific limitation. Forpreparing the resin composition, various methods can be employed as longas they are methods which are generally used for effectingmelt-kneading. For example, there can be employed a method in which aphosphoric acid ester and an inorganic filler in a scale form are addedto a resin in a molten form, followed by mixing, and a method in whichall of the above-mentioned components are first mixed together andsubsequently the resultant mixture is melt-kneaded. In the preparationof the thermoplastic resin composition to be used in the presentinvention, conventionally known kneading machines, such as an extruder,a heating roll, a kneader or a Banbury mixer, can be used.

The thermoplastic resin composition to be used for preparing the highprecision resin mechanical part of the present invention for use in anoffice automation machine may contain various additives, such as anantioxidant (e.g., a phenolic antioxidant, a phosphoric antioxidant or ahindered phenolic antioxidant), a stabilizer, a colorant (e.g., titaniumoxide or carbon black), a lubricant (e.g., a metallic soap), aflowability agent, and a reinforcing elastomer containing astyrene-butadiene block copolymer, polyester amide or the like, as longas the excellent effects of the present invention are not impaired. Theabove-mentioned additives can be used in such amounts as generallyemployed.

The term "high precision resin mechanical part for use in an officeautomation machine" is used herein as a general term for defining highprecision mechanical parts to be used for precision machines which arerequired to function with high accuracy and high precision. There is noparticular limitation with respect to the high precision mechanicalparts. As high precision mechanical parts, for example, (1) mechanicalparts for a machine in which writing and reading are done with lightand/or magnetism; (2) mechanical parts which are required to hold otherparts at predetermined positions in an accurate and precise manner(e.g., chassis); and (3) mechanical parts which are required to beengaged (or fitted) or slide relative to other parts in an accurate andprecise manner, can be mentioned. However, the high precision mechanicalparts are not limited to those mentioned above. Examples of mechanicalparts (1) include chassis for a driving device of a CD-ROM, awriting-type optical (or magnetic) disk, an FD (floppy disk), a HD (harddisk) and the like. Examples of mechanical parts (2) include chassis fora printer, a copier, a personal computer, a facsimile machine and thelike. Examples of mechanical parts (3) include a tray for a drivingdevice of a CD-ROM. However, the high precision resin mechanical partsof the present invention for use in an office automation machine are notlimited to those mentioned above.

Therefore, as specific examples of office automation machines for whichthe high precision resin mechanical part of the present invention isused, there can be mentioned copiers, printers, facsimile machines,personal computers, word processors, portable communication apparatus,composite machines composed thereof, and other machines (e.g.,computers, game machines, sound-reproducing systems and audio-visualmachines) in which writing and reading are done with light and/ormagnetism on disks (namely, disks as information media), such as a CD(compact disk), a CD-ROM, a LD (laser disk), a magneto-optical disk MD(trademark minidisk)!, an optical disk, a FD (floppy disk) and a HD(hard disk).

It is a requisite that the above-mentioned mechanical parts haveexcellent molded form characteristics, mechanical properties (e.g.,rigidity and strength), heat resistance, flame retardancy, dimensionalprecision and dimensional stability, and these excellent characteristicsand properties must be satisfactorily maintained even under stringentconditions. That is, the characteristics and properties of themechanical parts must not deteriorate at high temperature (e.g., at atemperature which is only about 30° C. lower than the heat distortiontemperature) and at high humidity. Among the above-mentioned properties,the requirements for the dimensional precision and dimensional stabilityare most strict in the mechanical parts. That is, it is required thatthe mechanical parts exhibit small dimensional change under hightemperature and high humidity conditions and be unlikely to suffer froma dimensional strain, such as warpage. With respect to conventionalmechanical parts which are made by injection molding a reinforced resincontaining only a fibrous inorganic filler (e.g., glass fibers), thereis a disadvantage such that warpage occurs at high temperature, leadingto a dimensional strain. Such a disadvantage is caused due to the largelinear expansion coefficient anisotropy inside of the molded product(the large anisotropy is caused by the orientation of the fibrousinorganic filler). On the other hand, other types of conventionalmechanical parts made of a reinforced resin containing aphosphorus-containing flame retardant, such as triphenyl phosphate orcresyl diphenylphosphate, also have a disadvantage in that the flameretardancy and appearance (e.g., blister) of the mechanical part arelikely to be lowered due to the flame retardant denaturation caused bymoisture absorption under high temperature and high humidity conditions.

However, the high precision mechanical part of the present invention cansurprisingly maintain high dimensional precision even under hightemperature and high humidity conditions.

In addition, it has unexpectedly been found that the high precisionmechanical part of the present invention has very small anisotropy inrigidity and strength inside of the molded product due to theincorporation of an inorganic filler in a scale form, so that themechanical part have excellent vibration characteristics. With respectto the vibration characteristics, the important factors arevibration-damping property and characteristic resonance frequency.

The term "vibration-damping property" means a property which can damp avibration. In general, plastics have a good vibration-damping propertyas compared to metallic materials, such as sheet metals and die-castedaluminum, since plastics exhibit a viscoelastic behavior. Plastics,however, have poor rigidity. For overcoming such poor rigidity, plasticsare generally reinforced with a fibrous inorganic filler. However, it iswell known that such reinforced plastics frequently have poorvibration-damping property.

However, it has unexpectedly been found that the mechanical part of thepresent invention, which is made of a resin composition containing aninorganic filler in a scale form, have excellent vibration-dampingproperty. The mechanism by which the excellent vibration-dampingproperty is exhibited by the mechanical part of the present inventionhas not yet been elucidated; however, it is presumed that such anexcellent vibration-dispersing property of the mechanical part of thepresent invention is exerted by the dispersion of the vibration.

The vibration-damping property of the mechanical part of the presentinvention can be more improved by incorporating a small amount of aresin component which has a glass transition temperature (Tg) at aroundroom temperature. Examples of such resin components include a rubbercomponent, such as an acrylic rubber; an elastomer component, such as anethylene-propylene rubber; and an olefin polymer resin.

The term "characteristic resonance frequency" means a resonancefrequency characteristic of a shaped article, and the characteristicresonance frequency depends on the morphology of the shaped article, andthe rigidity and density of the material of the shaped article. When themorphology of the shaped article is not varied, the characteristicresonance frequency of the shaped article is proportional to the squareroot of a value which is obtained by dividing the rigidity of thematerial by the density of the material. Although plastics generallyhave small densities as compared to metallic materials, such as sheetmetals and die-casted aluminum, the rigidities of plastics are extremelysmaller than those of metallic materials, so that plastics have smallcharacteristic resonance frequencies. In general, the vibration of amotor in operation in a machine and the vibration occurring around sucha machine have a frequency of less than 300 Hz. Therefore, forpreventing a mechanical part for use in a high precision machine frombeing resonated, it is preferred that the mechanical part have acharacteristic resonance frequency of 300 Hz or higher, which is outsidethe frequency ranges of the vibration of a motor in operation and of thevibration occurring around the machine.

It has unexpectedly been found that with respect to the mechanical partof the present invention comprising a specific resin composition, theresonance property value (characteristic resonance frequency) determinedby computer simulation is well in agreement with the resonance propertyvalue determined by an actual measurement of the vibration of themechanical part, so that the mechanical part of the present inventionhas extremely high reproducibility in resonance property. By contrast,the conventional mechanical parts which are made by molding a resincomposition containing only a fibrous inorganic filler, exhibitcomplicated resonance characteristics such that the resonance propertyvalue calculated by computer simulation or calculated from the value ofthe flexural modulus of elasticity and the value of the density of thematerial of the mechanical part (these values are available from thegeneral data book for properties of various materials) is not always inagreement with the actually measured resonance properties value. A goodagreement between the predicted resonance property value calculated bycomputer simulation and the actual resonance property value, as in thecase of the mechanical part of the present invention, is extremelyadvantageous in designing a high precision mechanical part.

It is quite unexpected that the mechanical part of the present inventionexhibits the above-mentioned excellent vibration properties, and theseexcellent vibration properties are totally unexpected from theconventional techniques. Such excellent vibration properties areespecially important in mechanical parts for use in a precisionapparatus, such as a driving device (having a rotating part) for aCD-ROM.

The above-mentioned mechanical parts are required to have extremely highdimensional precision. For example, with respect to an optical chassisof a facsimile machine which chassis holds an optical lens for readinginformation, and a traverse base chassis of a CD-ROM drive, it isrequired that the dimensional precision be such that any errors ordeviations must be on the order of several tens of μm. Furthermore, itis also required that such a mechanical part satisfactorily maintain thedimensional precision thereof even when the change in ambienttemperature change would occur. In other words, it is required that thelinear expansion coefficient and the anisotropy of the linear expansioncoefficient be small. The high precision mechanical part of the presentinvention has, for example, the following dimensional precisioncharacteristics:

(1) a dimensional tolerance of ±100 μm, preferably ±50 μm, morepreferably ±25 μm per 100 mm (predetermined or designed);

(2) an absolute value of warpage of 1 mm or less, preferably 800 μm orless, more preferably 500 μm or less per 100 mm (predetermined ordesigned); and

(3) an absolute value of flatness of 1 mm or less, preferably 800 μm orless, more preferably 500 μm or less.

The molding method for a resin composition for the production of themechanical part of the present invention for use in an office automationmachine is not particularly limited. However, in general, an injectionmolding method can be advantageously used. In the injection moldingmethod, it is desirable to minimize the flow strain which is generatedin the molded product during the molding process. When the flow strainis large, a large molecular orientation strain remains in the moldedproduct. The molecule orientation strain causes problems such that themolding shrinkage ratio becomes non-uniform, resulting in warpage, andthe practical heat resistance of the molded product becomes poor. In theinjection molding, it is desirable that the gate of a mold and themolding conditions be, respectively, so designed and chosen that theflow strain can be as small as possible.

It has been found that when gas-assisted injection molding is employedfor producing the mechanical part of the present invention, thedimensional accuracy of the produced mechanical part is remarkablyimproved as compared to the dimensional accuracy of the mechanical partproduced by usual injection molding. That is, in molding the resincomposition, the gas-assisted injection molding is extremely effectivefor suppressing the flow strain of the resin. Particularly, thegas-assisted injection molding is very effective for preparing a moldedproduct having a thickness as small as 1.5 mm or less, in which flowstrain is likely to occur. In the methods for gas-assisted injectionmolding, a liquid can also be used instead of gas. With respect to thegas-assisted injection molding, reference can be made to, for example,U.S. Pat. Nos. 4,824,732, 4,923,666, 4,101,617 and 5,173,241.

Further, it has also been found that the mechanical part produced bygas-assisted injection molding has not only excellent dimensionalprecision at room temperature but also improved dimensional stability athigh temperatures. This is unexpected from the conventionally knowneffects of gas-assisted injection molding.

In the present invention, when gas-assisted injection molding isemployed, the adverse influence of the molecular orientation (residualset) of the molded resin on the molded products can be minimized, sothat mechanical parts having high dimensional precision can be obtained.

Creep resistance is one of the characteristics required for resinmechanical parts. The high precision resin mechanical part of thepresent invention unexpectedly has high creep resistance as compared tothe conventional resin mechanical parts. That is, the rate of distortionof the mechanical part of the present invention is low even when themechanical part is placed under stress for a prolonged period of time.The reason for this has not yet been exactly elucidated; however, it ispresumed that the high creep resistance of the mechanical part of thepresent invention is ascribed to the specific flame retardant used.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in more detail withreference to the following Examples and Comparative Examples, but theyshould not be construed as limiting the scope of the present invention.

In the Examples and Comparative Examples, various properties of themolded products are measured as follows. Specimens are prepared from thethermoplastic resin composition by injection molding, and the propertiesof the specimens are determined according to the following test methods.

(1) Heat distortion temperature

The heat distortion temperature of a specimen is measured in accordancewith ASTM-D648.

(2) Flexural modulus

The flexural modulus of a specimen is measured in accordance withASTM-D790.

(3) Izod impact strength

The Izod impact strength of a 1/4 inch-thick, notched specimen ismeasured in accordance with ASTM-D256.

(4) Flame retardancy

The flame retardancy of a 1/16 inch-thick, strip-shaped specimen ismeasured in accordance with the method described in UL-Subject 94 (withrespect to this method, see, for example, U.S. Pat. No. 4,966,814).

(5) Warpage (as measured by "Asahi Kasei Method")

The maximum magnitude of warpage (mm) of a specimen is measured using aflat plate (150 mm×150 mm×3 mm) and a feeler gauge.

The smaller the maximum magnitude of the warpage, the better thedimensional precision.

(6) Linear expansion coefficient

The linear expansion coefficient of a 1/8 inch-thick dumbbell specimenfor use in a tensile test is measured at the temperature of -30 to +60°C. in accordance with ASTM-D696. In the measurement, the linearexpansion coefficient in the flow direction of the resin composition andthe linear expansion coefficient in a direction perpendicular to theflow direction of the resin composition are measured using a wireresistance strain gauge. Prior to the measurement, the specimen issubjected to annealing, thereby removing any strain thereof, andpre-treated in accordance with ASTM-D618.

(7) Anisotropy of the linear expansion coefficient

The anisotropy of the linear expansion coefficient in the presentinvention means the ratio of the linear expansion coefficient in thedirection perpendicular to the flow direction to the linear expansioncoefficient in the flow direction. The closer to 1 the above-mentionedratio is, the smaller the anisotropy of the linear expansion coefficientof the resin composition. The resin composition to be used for producingthe flame retardant, high precision resin mechanical part for use in anoffice automation machine needs to have a linear expansion coefficientanisotropy of 2 or less.

(8) Exposure test at high temperature and high humidity

With respect to the PPE resins, an exposure test at high temperature andhigh humidity is conducted by exposing a 1/16 inch-thick strip-shapedspecimen to saturated steam having a temperature of 121° C. and apressure of 2 atm. for 96 hours. With respect to the PC resins, anexposure test-at high temperature and high humidity is conducted bydipping a 1/16 inch-thick strip-shaped specimen in hot water at 95° C.for 150 hours.

(9) Appearance

The appearance of the molded products in a tray form as shown in FIG. 1is evaluated by visual observation. Ten thousand trays are moldedcontinuously.

(10) Warpage of tray

A tray as shown in FIG. 1 is placed on a mold platen and fixed thereto.The magnitude of the warpage of the tray is determined by measuring thedimension of the tray at individual sites thereof in Z direction(vertical direction), and the clearances (warpage) between the moldplaten and the individual sites of the tray, using a coordinatemeasuring machine (Model AE 122, manufactured and sold by MitsutoyoCorporation, Japan). The measured warpage is used as a criterion forevaluating the dimensional precision.

The phosphoric acid esters A-G as shown below are used in the Examplesand Comparative Examples.

Phosphoric acid ester A is bisphenol A-polycresyl phosphate representedby the following formula (IV): ##STR7## wherein n represents an integerof from 1 to 3.

Phosphoric acid ester B is bisphenol A-polyxylenyl phosphate representedby the following formula (V): ##STR8## wherein n represents an integerof from 1 to 3.

Phosphoric acid ester C is bisphenol A-poly(2,6-xylenyl)phosphaterepresented by the following formula (VI): ##STR9## wherein n representsan integer of from 1 to 3.

Phosphoric acid ester D is bisphenol A-polydiphenyl phosphaterepresented by the following formula (VII): ##STR10## wherein nrepresents an integer of from 1 to 3.

Phosphoric acid ester E is resorcinol-polyphenyl phosphate representedby the following formula (VIII): ##STR11## wherein n represents aninteger of from 1 to 3.

Phosphoric acid ester F is hydroquinone-polyphenyl phosphate representedby the following formula (IX): ##STR12## wherein n represents an integerof from 1 to 3.

Phosphoric acid ester G is triphenylphosphate (trade name: TPP,manufactured and sold by Daihachi Chemical Industry Co., Ltd.)represented by the following formula (X): ##STR13##

EXAMPLES 1 TO 4 AND COMPARATIVE EXAMPLES 1 TO 3

Pellets are produced from resin compositions by extrusion kneading,using a PCM-30 twin-screw extruder (manufactured and sold by IkegaiCorporation, Japan) at a cylinder temperature of 320° C. The resincompositions are composed of a poly(2,6-dimethyl-1,4-phenylene)etherresin (hereinafter referred to simply as "PPE") which exhibits anintrinsic viscosity (η) of 0.52 at 30° C. in chloroform, arubber-modified polystyrene resin (Asahi Chemical Polystyrene H9104manufactured and sold by Asahi Chemical Industry Co., Ltd., Japan), apolystyrene resin (Asahi Chemical Polystyrene 685 manufactured and soldby Asahi Chemical Industry Co., Ltd., Japan), each of theabove-mentioned phosphoric acid esters A to G as a flame retardantagent, a glass flake (Micro glass fleka REFG-302 sold by NIPPON SHEETGLASS Co., Ltd., Japan) as an inorganic filler, and a mixture of zincoxide/zinc sulfide /MARK 2112 (ADEKA ARGUS Chemical Co., Ltd., Japan)(weight ratio of the three components=1:1:1) as a stabilizing agent thechemical nomenclature of MARK 2112 istris(2,4-di-t-butylphenyl)phosphite!. The PPE, rubber-modifiedpolystyrene resin, polystyrene resin, phosphoric acid ester, glassflake, and stabilizing agent are used in amount ratios as shown inTable 1. Using an injection molding machine, the obtained pellets arethen subjected to injection molding at a cylinder temperature of 290°C., to thereby obtain 1/16 inch-thick specimens for use in a test forflame retardancy.

With respect to the obtained specimens, the flame retardancy ismeasured, and an exposure test at high temperature and high humidity isconducted. Subsequently, in order to evaluate a mechanical part for usein a driving device for a CD-ROM, a tray as shown in FIG. 1 is made fromthe above-mentioned pellets by injection molding, using an injectionmolding machine at a cylinder temperature of 290° C. The temperature ofthe mold is set at 80° C. Ten thousand trays are molded continuously,and the appearances of the obtained trays and the mold inner wall areevaluated. The degree of volatilization of the resin composition isevaluated by visually observing the amount of smoking from a nozzle ofthe injection molding machine in the purging (injection without using amold) test of the resin composition.

Results are shown in Table 1.

In Examples 1 to 4, the obtained trays exhibit a characteristicresonance frequency value which is well in agreement with thecharacteristic resonance frequency value calculated by computersimulation.

EXAMPLES 5 TO 10 AND COMPARATIVE EXAMPLES 4 AND 5

Pellets are produced from resin compositions by extrusion kneading,using a PCM-30 twin-screw extruder (manufactured and sold by IkegaiCorporation, Japan) at a cylinder temperature of 320° C. The resincompositions are composed of a PPE which exhibits an intrinsic viscosity(η) of 0.52 at 30° C. in chloroform, a HIPS (Asahi Chemical PolystyreneH9104 manufactured and sold by Asahi Chemical Industry Co., Ltd.,Japan), a PS (Asahi Chemical Polystyrene 685 manufactured and sold byAsahi Chemical Industry Co., Ltd., Japan), the above-mentionedphosphoric acid ester A as a flame retardant agent, and, as inorganicfillers, a glass fiber (RES03-TP1051, manufactured and sold by NIPPONSHEET GLASS Co., Ltd., Japan), a glass flake (Micro glass fleka REFG-302sold by NIPPON SHEET GLASS Co., Ltd., Japan) and mica (Suzorite Mica200KI, manufactured and sold by Kuraray Co., Ltd., Japan). The PPE,HIPS, PS, phosphoric acid ester, and inorganic filler are used in amountratios as shown in Table 2.

The properties of the resin composition are determined in accordancewith the above-mentioned test methods.

Results are shown in Table 3.

Subsequently, in order to evaluate a mechanical part for use in adriving device for a CD-ROM, a tray as shown in FIG. 1 is made from theabove-mentioned pellets by injection molding, using an injection moldingmachine at a cylinder temperature of 290° C. The temperature of the moldis set at 80° C. The dimensional precision (warpage) of each of theobtained trays is measured.

Results are shown in Table 4.

In Comparative Example 4, as shown in Table 3, the resin compositioncontaining glass fibers alone as an inorganic filler exhibits a largewarpage and a large anisotropy of the linear expansion coefficient (anindex of dimensional precision). In Comparative Example 5, the resincomposition containing glass beads (EGB731A, manufactured and sold byToshiba Ballotini Co., Ltd. Japan) alone as an inorganic filler exhibitsa small warpage and a small anisotropy of linear expansion coefficient,but the flexural modulus thereof is low. Results of the measurementshown in Table 4 indicate that there is a correlation between thewarpage of the trays shown in Table 4 and each of the warpage and theanisotropy of the linear expansion coefficient which are shown in Table3, however, there is no correlation between those data which aremeasured with respect to the trays produced from the resin compositionscontaining glass beads or mica alone as an inorganic filler. That is,the larger the warpage and the anisotropy of the linear expansioncoefficient shown in Table 3, the larger the warpage of the tray shownin Table 4.

In Examples 5 to 10, the obtained trays exhibit a characteristicresonance frequency value which is well in agreement with thecharacteristic resonance frequency value calculated by computersimulation.

EXAMPLES 11 TO 14 AND COMPARATIVE EXAMPLES 6 TO 8

Pellets are produced from resin compositions by extrusion kneading,using a PCM-30 twin-screw extruder (manufactured and sold by IkegaiCorporation, Japan) at a cylinder temperature of 310° C. The resincompositions are composed of a polycarbonate resin Iupilon S-1000,manufactured and sold by Mitsubishi Engineering Plastics Corp., Japan),each of the above-mentioned phosphoric acid esters A to G as a flameretardant agent, and a glass flake (Micro glass fleka REFG-302 sold byNIPPON SHEET GLASS Co., Ltd., Japan) as an inorganic filler. Thepolycarbonate resin, phosphoric acid ester and glass flake are used inamount ratios as shown in Table 5. Using an injection molding machine,the obtained pellets are then subjected to injection molding at acylinder temperature of 280° C., to thereby obtain 1/16 inch-thickspecimens for use in a test for flame retardancy.

With respect to the obtained specimens, the flame retardancy ismeasured, and an exposure test at high temperature and high humidity isconducted. Subsequently, in order to evaluate a mechanical part for usein a driving device for a CD-ROM, a tray as shown in FIG. 1 is made fromthe above-mentioned pellets by injection molding, using an injectionmolding machine at a cylinder temperature of 280° C. The temperature ofthe mold is set at 80° C. Ten thousand trays are molded continuously,and the appearances of the obtained trays and the mold inner wall areevaluated. The degree of volatilization of the resin composition isevaluated by visually observing the amount of smoking from a nozzle ofthe injection molding machine in the purging test of the resincomposition.

Results are shown in Table 5.

In Examples 11 to 14, the obtained trays exhibit a characteristicresonance frequency value which is well in agreement with thecharacteristic resonance frequency value calculated by computersimulation.

EXAMPLES 15 TO 20 AND COMPARATIVE EXAMPLES 9 AND 10

Pellets are produced from resin compositions by extrusion kneading,using a PCM-30 twin-screw extruder (manufactured and sold by IkegaiCorporation, Japan) at a cylinder temperature of 310° C. The resincompositions are composed of a polycarbonate resin (Iupilon S-1000,manufactured and sold by Mitsubishi Engineering Plastics Corp., Japan),the above-mentioned phosphoric acid ester A and, as inorganic fillers, aglass fiber (RES03-TP1051, manufactured and sold by NIPPON SHEET GLASSCo., Ltd., Japan), a glass flake (Micro glass fleka REFG-302, and micawhich is surface-treated with aminosilane (Repco S200HG-CT, manufacturedand sold by REPCO LTD., Japan). The polycarbonate resin, phosphoric acidester A and inorganic filler are used in amount ratios as shown in Table6. The properties of the resin compositions are determined in accordancewith the above-mentioned test methods.

Results are shown in Table 7.

Subsequently, in order to evaluate a mechanical part for use in adriving device for a CD-ROM, a tray as shown in FIG. 1 is made from theabove-mentioned pellets by injection molding, using an injection moldingmachine at a cylinder temperature of 280° C. The temperature of the moldis set at 80° C. The dimensional precision (warpage) of each of theobtained trays is measured.

Results are shown in Table 8.

In Comparative Example 9, as shown in Table 7, the resin compositioncontaining glass fibers alone as an inorganic filler exhibits a largewarpage and a large anisotropy of the linear expansion coefficient (anindex of dimensional precision). In Comparative Example 10, the resincomposition containing glass beads alone as an inorganic filler exhibitsa small warpage and a small anisotropy of linear expansion coefficient,but a flexural modulus thereof is low. Results of the measurement shownin Table 8 indicate that there is a correlation between the warpage ofthe trays shown in Table 8 and each of the warpage and the anisotropy ofthe linear expansion coefficient which are shown in Table 7, except forthe data measured with respect to the trays produced from the resincompositions containing glass beads as an inorganic filler.

In Examples 15 to 20, the obtained trays exhibit a characteristicresonance frequency value which is well in agreement with thecharacteristic resonance frequency value calculated by computersimulation.

EXAMPLES 21 TO 26 AND COMPARATIVE EXAMPLES 11 TO 12

Preparation of ABS resin

Seven hundred fifty parts by weight of a butadiene latex (which has arubber content of 40% by weight) having an average particle diameter of0.30 μm and 1 part by weight of an emulsifier (disproportionatedpotassium rosinate) are charged in a polymerization tank and heated to70° C. with stirring under flowing of nitrogen. To the resultant mixtureare added a mixed liquid comprising 200 parts by weight ofacrylonitrile, 500 parts by weight of styrene, 0.8 part by weight ofcumene hydroperoxide and 0.7 part by weight of t-dodecylmercaptan, andan aqueous solution which is obtained by dissolving, into 500 parts byweight of distilled water, 1.0 part by weight of sodium formaldehydesulfoxylate, 0.10 part by weight of ferrous sulfate (FeSO₄.7H₂ O) and0.2 part by weight of disodium ethylenediaminetetraacetate over 6 hourswith stirring, to thereby perform a polymerization reaction.

Stirring is further continued for 2 hours to complete thepolymerization. The polymerization degree of monomers is 94%. An aqueoussolution of dilute sulfuric acid is added to the reaction mixture tocoagulate the formed latex of a graft copolymer. The coagulated latex iswashed, dehydrated and dried, to thereby obtain a white ABS resin.

Preparation of AS resin

0.4 part by weight of potassium persulfate and 2.0 parts by weight ofpotassium rosinate are dissolved in 180 parts by weight of distilledwater. To the resultant solution are added 70 parts by weight ofstyrene, 30 parts by weight of acrylonitrile and 0.2 part by weight ofdodecylmercaptan, and reacted at 70° C. for 4 hours, to thereby obtainan aromatic vinyl copolymer. The polymerization degree of monomers is94%. An aqueous solution of dilute sulfuric acid is added to theresultant reaction mixture to agglomerate the formed copolymer. Theresultant copolymer is washed, dehydrated and dried, to thereby obtain awhite AS resin.

Production of a mechanical part

Forty parts by weight of a polycarbonate resin having a weight averagemolecular weight of 25,000, 12 parts by weight of the ABS resin, 8 partsby weight of the AS resin and 10 parts by weight of phosphoric acidester A are mixed by means of a Henschel mixer. The resultant mixture ismelt-kneaded with a filler shown in Table 9 (which is used in the amountratio shown in Table 9), using a PCM-30 twin-screw extruder in which acylinder temperature is set at 250° C., to thereby obtain reinforcedresin pellets. Subsequently, in order to evaluate a mechanical part foruse in a driving device for a CD-ROM, a tray as shown in FIG. 1 is madefrom the above-obtained pellets by injection molding, using an injectionmolding machine at a cylinder temperature of 260° C. and a moldtemperature of 60° C. The dimensional precision (warpage) of the traysis measured. Results are shown in Table 8.

As shown in Table 8, there is a correlation between the warpage of thetrays in these Examples and Comparative Examples and the warpage oftrays in Examples 15 to 20 and Comparative Examples 9 and 10 above,except for the warpage of trays measured with respect to thepolycarbonate resin composition containing glass beads alone as aninorganic filler.

In Examples 21 to 26, the obtained trays exhibit a characteristicresonance frequency value which is well in agreement with thecharacteristic resonance frequency value calculated by computersimulation.

EXAMPLES 27 TO 30

A molded resin article in a tray form is produced by gas-assistedinjection molding at a cylinder temperature of 280° C. and a moldtemperature of 80° C., using individually PPE resin compositions ofExamples 5 and 6 and PC resin compositions of Examples 15 and 16. Theshot volume of the molten resin is 95% of the full shot. Gas (N₂) isintroduced from the gate into a molten resin mass immediately aftercompletion of the injection of the molten resin. The gas is held at apressure of 150 kg/cm² for 20 seconds. Then, the molten resin mass iscooled for one minute and the obtained molded resin article is releasedfrom the mold. The dimensional precision (warpage) of the obtained traysis determined. Results are shown in Table 10. The trays produced bygas-assisted injection molding in Examples 27 to 30 have a more improveddimensional precision than the trays produced by ordinary injectionmolding in Examples 5 and 6 and Examples 15 and 16.

In Examples 27 to 30, the obtained trays exhibit a characteristicresonance frequency value which is well in agreement with thecharacteristic resonance frequency value calculated by computersimulation.

EXAMPLES 31 TO 36

Chassis for holding an optical element as shown in FIG. 2 are producedby gas-assisted injection molding and ordinary injection molding at acylinder temperature of 280° C. and a mold temperature of 80° C., usingrespectively the PPE resin compositions of Examples 5 and 6, and the PCresin compositions of Examples 15 and 16. Likewise, chassis for holdingan optical element as shown in FIG. 2 are produced by gas-assistedinjection molding and ordinary injection molding at a cylindertemperature of 260° C. and a mold temperature of 60° C., usingrespectively the PC/ABS resin compositions of Examples 21 and 22. Theflatness of the section shown by hatching in FIG. 2 of the obtainedmolded resin article, is determined. Then, the change in dimension (thechange in the flatness) of the hatched section of the molded resinarticle is determined after the molded article is subjected to a heatexposure test for 250 hours in an oven at 60°.

In the gas-assisted injection molding, the shot volume of the moltenresin is 97% of the full shot. Gas (N₂) is introduced from a portion ofthe cavity inner well into a molten resin mass immediately aftercompletion of the injection of the molten resin. The gas is held at apressure of 200 kg/cm² for 12 seconds. Then, the molten resin mass iscooled for one minute and the obtained shaped resin article is releasedfrom the mold.

The dimensional precision of the shaped resin article is measured in thefollowing manner. The molded resin article is secured onto a moldplaten. Then, the flatness of the section, shown by the hatching in FIG.2, is determined by means of a coordinate measuring machine (Model AE122, manufactured and sold by Mitsutoyo Corporation, Japan) using ameasuring program (Geopack 400, manufactured and sold by Mitsutoyocorporation, Japan). In accordance with the above-mentioned program, theflatness is determined as follows. With respect to the above-mentionedhatched section, a plurality of measurement sites (at least 15 sites)are arbitarily selected. From the selected measurement sites, acalculated plane is obtained by calculation according to the leastsquare method. Then, two planes are imagined on both sides of thecalculated plane, which two planes are in parallel to the calculatedplane. A minimum distance value is obtained with respect to distances atwhich distances the above-mentioned two parallel planes are located soas to form therebetween a space capable of accomodating therein allmeasurement sites. Such a minimum value (mm) is defined as the flatness.The larger the value of flatness thus determined, the lower theflatness. Results are shown in Table 11.

In Examples 31 to 36, the obtained chassis exhibit a characteristicresonance frequency value which is well in agreement with thecharacteristic resonance frequency value calculated by computersimulation.

                                      TABLE 1    __________________________________________________________________________    (Formulation of resin composition (parts by weight))                  Example Nos.    Comparative Example Nos.    Components    1   2   3   4   1    2    3    __________________________________________________________________________    Poly(2,6-dimethyl-1,4-                  40  40  40  40  40   40   40    phenylene)ether    Polystyrene H9104(HIPS)                  15  15  15  15  15   15   15    Polystyrene 685 (GPPS)                  5   5   5   5   5    5    5    Zinc oxide/zinc sulfide/                  0.3 0.3 0.3 0.3 0.3  0.3  0.3    MARK 2112    Phosphoric acid ester A                  10    Phosphoric acid ester B                      10    Phosphoric acid ester C                          10    Phosphoric acid ester D   10    Phosphoric acid ester E       10    Phosphoric acid ester F            10    Phosphoric acid ester G                 10    Micro glass fleka REFG-302                  30  30  30  30  30   30   30    (glass flake)    Flame retardancy (UL-94)                  V-1 V-1 V-1 V-1 V-1  V-1  V-1    before exposure test at    high temperature and humidity    Flame retardancy (UL-94)                  V-1 V-1 V-1 V-1 V-2  V-2  V-2    after exposure test at    high temperature and humidity    Smoking amount                  Almost                      Almost                          Almost                              Almost                                  Almost                                       Almost                                            Much    (visual observation)                  none                      none                          none                              none                                  none none    Appearances of            2000th shot                  No  No  No  No  No   No   *)    molded product                  change                      change                          change                              change                                  change                                       change    and mold cavity            5000th shot                  No  No  No  No  *)   *)   *)                  change                      change                          change                              change            10000th shot                  No  No  No  No  *)   *)   *)                  change                      change                          change                              change    Appearance change after                  No  No  No  No  Discolo-                                       Discolo-                                            Discolo-    exposure test at high                  change                      change                          change                              change                                  ration                                       ration                                            ration    temperature and humidity      and  and                                  Blister                                       Blister    __________________________________________________________________________     *Note: Oily matter deposit was observed at a portion of product which     corresponds to the forward end of the resin flow and observed at a portio     of the mold inner wall which corresponds to the forward end of the resin     flow.

                                      TABLE 2    __________________________________________________________________________    (Formulation of resin composition (parts by weight))                                      Comparative                    Example Nos.      Example Nos.    Components      5  6  7  8  9  10 4   5    __________________________________________________________________________    Poly(2,6-dimethyl-1,4-phenylene)                    40 40 40 40 40 40 40  40    ether    Polystyrene H9104(HIPS)                    15 15 15 15 15 15 15  15    Polystyrene 685 (GPPS)                    5  5  5  5  5  5  5   5    Zinc oxide/zinc sulfide/MARK 2112                    0.3                       0.3                          0.3                             0.3                                0.3                                   0.3                                      0.3 0.3    Phosphoric acid ester A                    10 10 10 10 10 10 10  10    Micro glass fleka REFG-302                    30 15 15 -- 7.5                                   -- --  --    (glass flake)    RES03-TP1015F (glass fiber)                    -- 15 -- 15 15 -- 30  --    Suzorite Mica 200KI                    -- -- 15 15 7.5                                   30 --  --    Glass beads EGB731A                    -- -- -- -- -- -- --  30    __________________________________________________________________________

                                      TABLE 3    __________________________________________________________________________    (Characteristics of molded products)                                                        Comparative                       Example Nos.                     Example Nos.                       5     6    7     8    9    10    4    5    __________________________________________________________________________    Warpage           Asahi Kasei                  mm   0.15  0.25 0.18  0.27 0.24 0.2   0.63 0.45           Method    Flexural           ASTM-D790                  kg/cm.sup.2                       66000 76000                                  64000 79000                                             77000                                                  62000 66000                                                             45000    modulus    Izod impact           ASTM-D256,                  kg · cm/                       3.0   4.9  3.0   5.0  5.0  2.0   5.2  4.0    strength           notched                  cm    Linear Flow   mm/mm/                       3.2   3.1  3.0   3.0  3.0  3.0   1.7  4.8    expansion           direction                  ° C.    coefficient           Direction                  mm/mm/                       3.8   5.5  4.2   5.6  5.5  4.0   5.9  5.7    (-30 to +           perpendicular                  ° C.    60° C.) ×           to the flow    10.sup.-5           direction    Anisotropy of linear                       1.2   1.8  1.4   1.9  1.8  1.3   3.4  1.2    expansion coefficient    Heat   ASTM-D643                  ° C.                       100   100  100   100  100  100   102  105    distortion    temperature    Flame  UL-94  Class                       V-1   V-1  V-1   V-1  V-1  V-1   V-1  V-1    retardance    __________________________________________________________________________

                  TABLE 4    ______________________________________    (warpage of molded products)                               unit:mm!                                  Comparative    Measure-            Example Nos.          Example Nos.    ment site            5      6      7    8    9    10   4     5    ______________________________________    A       0.15   0.19   0.14 0.21 0.20 0.15 0.35  0.23    B       0.12   0.17   0.13 0.2  0.19 0.14 0.32  0.22    C       0.13   0.18   0.15 0.19 0.19 0.14 0.34  0.21    D       0.19   0.21   0.2  0.22 0.2  0.2  0.41  0.25    E (4.1#)            4.1    4.4    4.2  4.5  4.5  4.2  4.8   4.6    F (6.1#)            6.5    6.7    6.5  6.8  6.7  6.5  7.0   6.9    ______________________________________     Note: "#" shows predetermined value, and measured value indicated with     respect to E and F is predetermined value plus warpage value.

                                      TABLE 5    __________________________________________________________________________    (Formulation of resin composition (parts by weight))                   Example Nos.    Comparative Example Nos.    Components     11  12  13  14  6    7    8    __________________________________________________________________________    Iupilon S-1000 60  60  60  60  60   60   60    Phosphoric acid ester A                   10    Phosphoric acid ester B                       10    Phosphoric acid ester C                           10    Phosphoric acid ester D    10    Phosphoric acid ester E        10    Phosphoric acid ester F             10    Phosphoric acid ester G                  10    Micro glass fleka REFG-302                   30  30  30  30  30   30   30    (glass flake)    Flame retardancy (UL-94)                   V-0 V-0 V-0 V-0 V-0  V-0  V-0    before exposure test at    high temperature and humidity    Flame retardancy (UL-94)                   V-0 V-0 V-0 V-0 V-2  V-2  V-2    after exposure test at    high temperature and humidity    Smoking amount Almost                       Almost                           Almost                               Almost                                   Almost                                        Almost                                             Much    (visual observation)                   none                       none                           none                               none                                   none none    Appearances of             2000th shot                   No  No  No  No  No   No   *)    molded product and                   change                       change                           change                               change                                   change                                        change    mold cavity             5000th shot                   No  No  No  No  *)   *)   *)                   change                       change                           change                               change             10000th shot                   No  No  No  No  *)   *)   *)                   change                       change                           change                               change    Appearance change after                   No  No  No  No  Discolo-                                        Discolo-                                             Discolo-    exposure test at high                   change                       change                           change                               change                                   ration and                                        ration and                                             ration    temperature and humidity       Blister                                        Blister    __________________________________________________________________________     *Note: Oily matter deposit was observed at a portion of product which     corresponds to the forward end of the resin flow and observed at a portio     of the mold inner wall which corresponds to the forward end of the resin     flow.

                  TABLE 6    ______________________________________    (Formulation of resin composition (parts by weight))                              Comparative               Example Nos.   Example Nos    Components   15    16    17  18  19   20  9    10    ______________________________________    Iupilon S-1000                 60    60    60  60  60   60  60   60    Phosphoric acid ester A                 10    10    10  10  10   10  10   10    Micro glass fleka                 30    15    15  --  7.5  --  --   --    REFG-302 (glass flake)    RES03-TP1015F                 --    15    --  15  15   --  30   --    (glass fiber)    Repco S200HG-CT                 --    --    15  15  7.5  30  --   --    (mica)    Glass beads EGB731A                 --    --    --  --  --   --  --   30    ______________________________________

                                      TABLE 7    __________________________________________________________________________    (Characteristics of molded products)                                                        Comparative                       Example Nos.                     Example Nos.                       15   16    17   18    19   20    9    10    __________________________________________________________________________    Warpage           Asahi Kasei                  mm   0.13 0.20  0.17 0.23  0.22 0.17  0.35 0.15           Method    Flexural           ASTM-D790                  kg/cm.sup.2                       62000                            70000 53000                                       71000 68000                                                  51000 72000                                                             43000    modulus    Izod impact           ASTM-D256,                  kg · cm/                       7.0  9.0   6.2  8.0   8.5  4.2   12.5 7.0    strength           notched                  cm    Linear Flow   mm/mm/                       3.2  2.7   3.0  2.5   2.6  2.9   2.i  3.1    expansion           direction                  ° C.    coefficient           Direction                  mm/mm/                       4.0  4.8   4.2  4.8   4.7  4.3   5.3  4.2    (-30 to +           perpendicular                  ° C.    60° C.) ×           to the flow    10.sup.-5           direction    Anisotropy of linear                       1.25 1.8   1.4  1.92  1.8  1.48  2.52 1.35    expansion coefficient    Heat   ASTM-D643                  ° C.                       145  146   143  145   145  142   146  143    distortion    temperature    Flame  UL-94  Class                       V-0  V-0   V-0  V-0   V-0  V-0   V-0  V-0    retardance    __________________________________________________________________________

                                      TABLE 8    __________________________________________________________________________    (Warpage of molded products)                                                     unit:mm!    Measure-                                 Comparative    ment Example Nos.                        Example Nos.    site 15 16 17 18 19 20 21 22 23 24 25 26 9  10 11 12    __________________________________________________________________________    A    0.16            0.21               0.17                  0.22                     0.21                        0.18                           0.15                              0.2                                 0.15                                    0.21                                       0.2                                          0.16                                             0.35                                                0.16                                                   0.32                                                      0.17    B    0.13            0.19               0.15                  0.20                     0.20                        0.17                           0.13                              0.18                                 0.14                                    0.19                                       0.19                                          0.16                                             0.34                                                0.17                                                   0.33                                                      0.15    C    0.14            0.18               0.14                  0.19                     0.19                        0.16                           0.15                              0.19                                 0.17                                    0.19                                       0.19                                          0.17                                             0.32                                                0.18                                                   0.3                                                      0.17    D    0.2            0.24               0.21                  0.25                     0.23                        0.19                           0.19                              0.22                                 0.2                                    0.23                                       0.23                                          0.19                                             0.4                                                0.2                                                   0.38                                                      0.19    E (4.1#)         4.2            4.6               4.3                  4.6                     4.6                        4.4                           4.2                              4.5                                 4.2                                    4.5                                       4.6                                          4.4                                             4.8                                                4.4                                                   4.9                                                      4.5    F (6.1#)         6.6            6.9               6.6                  7.0                     6.9                        6.6                           6.5                              6.8                                 6.6                                    6.9                                       6.9                                          6.6                                             7.2                                                6.5                                                   7.1                                                      6.5    __________________________________________________________________________     Note: "#" shows predetermined value, and measured value indicated with     respect to E and F is predetermined value plus warpage value.

                  TABLE 9    ______________________________________    (Formulation of resin composition (parts by weight))                              Comparative               Example Nos.   Example Nos.    Components   21    22    23  24  25   26  11   12    ______________________________________    Polycarbonate resin                 40    40    40  40  40   40  40   40    ABS resin    12    12    12  12  12   12  12   12    AS resin     8     8     8   8   8    8   8    8    Phosphoric acid ester A                 10    10    10  10  10   10  10   10    Micro glass fleka                 30    15    15  --  7.5  --  --   --    REFG-302 (glass flake)    RES03-TP1015F                 --    15    --  15  15   --  30   --    (glass fiber)    Repco S200HG-CT                 --    --    15  15  7.5  30  --   --    (mica)    Glass beads EGB731A                 --    --    --  --  --   --  --   30    ______________________________________

                  TABLE 10    ______________________________________    (warpage of molded products)     unit: mm!               Example Nos.    Measurement site                 27     28         29   30    ______________________________________    A            0.10   0.12       0.11 0.13    B            0.08   0.11       0.07 0.11    C            0.09   0.12       0.09 0.12    D            0.12   0.14       0.12 0.14    E (4.1#)     4.1    4.3        4.2  4.3    F (6.1#)     6.2    6.3        6.2  6.3    ______________________________________     Note:     "#" shows predetermined value, and measured value indicated with respect     to E and F is predetermined value plus warpage value.

                  TABLE 11    ______________________________________    (Flatness of molded products)                               unit: mm!    Heat exposure test                  Example Nos.    60° C. × 250 hours                  31     32      33   34   35   36    ______________________________________    Flatness  Before  0.121  0.183 0.134                                        0.207                                             0.114                                                  0.178              the test    Gas-assisted              After   0.129  0.195 0.150                                        0.225                                             0.120                                                  0.190    injection molding              the test    Flatness  Before  0.162  0.281 0.235                                        0.323                                             0.156                                                  0.252              the test    Ordinary  After   0.179  0.310 0.265                                        0.364                                             0.170                                                  0.277    injection molding              the test    ______________________________________

INDUSTRIAL APPLICABILITY

The flame retardant, high precision resin mechanical part (for use in OAmachines) of the present invention is not only free from conventionallyexperienced disadvantages, such as denaturation, volatilization andbleeding of the flame retardant, but also has high dimensional precisionand excellent mechanical properties (e.g., mechanical strength andvibration-damping property), so that the mechanical part of the presentinvention can be advantageously used as a mechanical part for varioustypes of OA machines which are required to function with high accuracyand high precision.

We claim:
 1. A flame retardant, high precision resin mechanical part foruse in office automation machines required to function with highaccuracy and high precision, which is made by injection molding athermoplastic resin composition comprising:(A) 100 parts by weight of anamorphous thermoplastic resin; (B) 5 to 1 50 parts by weight of aninorganic filler in a flake form, which is comprised of at least onefiller selected from the group consisting of glass flakes and micaflakes, wherein said glass flakes have a weight average major diameterof 1,000 μm or less and a weight average aspect ratio of 5 or more andsaid mica flakes have a weight average diameter of 1,000 μm or less anda weight average aspect ratio of 10 or more; and (C) 3 to 50 parts byweight of a phosphoric acid ester represented by the following formula(I): ##STR14## wherein each of Q¹, Q², Q³ and Q⁴ independentlyrepresents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms;each of R¹, R², R³ and R⁴ independently represents a methyl group or ahydrogen atom; n represents an integer of 1 or more; each of n1 and n2independently represents an integer of from 0 to 2; and each of m1, m2,m3 and m4 independently represents an integer of from 1 to
 3. 2. Theflame retardant, high precision resin mechanical part according to claim1, wherein said injection molding is gas-assisted injection molding. 3.The flame retardant, high precision resin mechanical part according toclaim 1, wherein said inorganic filler in a flake form is comprised ofglass flakes.
 4. The flame retardant, high precision resin mechanicalpart according to claim 1, wherein said inorganic filler in a flake formis comprised of mica flakes.
 5. The flame retardant, high precisionresin mechanical part according to claim 1, wherein said inorganicfiller in a flake form is comprised of glass flakes and mica flakes. 6.The flame retardant, high precision resin mechanical part according toany one of claims 1 to 5, wherein said thermoplastic resin compositionfurther comprises a fibrous reinforcing filler, and wherein the totalweight of said inorganic filler in a flake form and said fibrousreinforcing filler is 150 parts by weight or less.
 7. The flameretardant, high precision resin mechanical part according to claim 6,wherein said fibrous reinforcing filler is present in an amount of from25 to 75% by weight, based on the total weight of said inorganic fillerin a flake form and said fibrous reinforcing filler.